Moisture content in foods affects many aspects of processing and storage, as well as quality and pathological activity. Understanding its behavior is very important in the food industry for designing effective long-term food management strategies, in particular transportation and storage. Most approaches found in the literature dealing with moisture in foods consist of measuring it as a function of relative humidity and temperature and then fitting the data to empirical or semi-empirical models for interpolation or correlation purposes. Most semi-empirical models are modifications of early gas adsorption models on hard surfaces, which fundamentally are not well suited to describe water in softer materials such as foods. In this work, we propose and use a more general framework based on equilibrium molecular thermodynamics to model and correlate equilibrium moisture content (EMC) in foods that takes into account other non-adsorption phenomena such as mixing and swelling of the biopolymers in foods. The framework is general, and the current model shows very good results correlating and modeling EMC. The model parameters provide insight into the nature of the water activity in food products, providing potentially useful information for food processing and modeling.